The invention herein relates to filter aids, especially diatomite, having a low soluble iron content. It also relates to a method for production of such low soluble iron filter aid.
In the manufacture or processing of a number of vegetable based beverages (notably beer, ale, wine and fruit juices) the beverage is filtered one or more times through granular heterogeneous filter media, usually diatomite. These filter media contain small amounts of various minerals and compounds, among which are iron compounds. A certain small portion of the iron content of the media is soluble in the vegetable beverages. This portion of the iron may be referred to as "beverage soluble iron" (often abbreviated "BSI").
The presence of higher levels of BSI dissolved in the beverage can be deleterious to the taste and long term stability ("shelf life") of the beverage. Consequently, it would be desirable to have a filter medium which is low in BSI content but which retains its desirable filtration and clarification properties.